Capacitor capacitance value online monitoring method, device and system and auxiliary discharge network

Abstract

The invention provides a capacitor capacitance value on-line monitoring method, device and system and an auxiliary discharge network, and the method comprises the steps: when a power converter is in an on-line operation state, collecting the voltage of a DC power supply for many times and recording a time point at a stage that a bipolar junction transistor is disconnected and a resistor is put into operation; determining the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor according to the starting time point when the bipolar junction transistor is disconnected and the resistor is put into operation, the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor, the resistance value of the resistor, the direct-current power supply voltage and the time point; the first and second capacitor branches are connected in parallel with the direct-current power supply; the first capacitor branch comprises a resistor and a first aluminum electrolytic capacitor which are connected in series; the second capacitance branch comprises a second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor. The capacitance value of the capacitor can be monitored on line, and the reliability of capacitor state monitoring is improved.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular, to a method, device, system and auxiliary discharge network for online monitoring of capacitor capacitance values. Background Art

[0002] With the increasing maturity of power electronics technology and control strategies, the health status of power converters has gradually become the main concern. As one of the most common components, capacitors play an important role in filtering ripple voltage, power decoupling and energy buffering. However, due to the susceptibility of capacitors to heat and electrical stress, their degradation rate is relatively high. Capacitor failures account for up to 30% of power converter failures. Compared with other types of capacitors, aluminum electrolytic capacitors (AECs) have a shorter lifespan. However, due to the advantages of large capacitance and low cost of aluminum electrolytic capacitors, they usually cannot be replaced by other types of capacitors. Therefore, monitoring the health status of AECs is crucial for improving the reliability of converters.

[0003] Currently, the common capacitor condition monitoring (CM) schemes are offline schemes, which require suspending the operation of the power converter and usually require a large amount of manual intervention and cannot be completed automatically. Another common capacitor condition monitoring scheme is a quasi-online CM scheme, which estimates the capacitance value using the charge and discharge curves under specific conditions (such as startup, shutdown and no-load); estimates the capacitance value by measuring the time constant of the capacitor and the discharge resistor; although the quasi-online CM method does not require additional current sensors or high sampling frequencies, continuous estimation cannot be achieved during normal operation. Summary of the Invention

[0004] In view of at least one problem in the prior art, the present application provides a method, device, system and auxiliary discharge network for online monitoring of capacitor capacitance values, which can monitor the capacitance value of a capacitor when the power converter is in an online operation state, and thus can improve the reliability of capacitor condition monitoring.

[0005] To solve the above technical problems, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a method for online monitoring of capacitor capacitance values, including:

[0007] When the power converter is in an online operation state, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the DC power supply voltage is collected multiple times and the corresponding time points are recorded.

[0008] Obtain the starting time point of the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0009] Based on the starting time point, the total output current, the resistance value, the DC power supply voltages collected each time and their respective corresponding time points, monitor and determine the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor;

[0010] Wherein, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0011] In one embodiment, during the stage when the bipolar junction transistor is in the off state and the resistor is put into operation, collecting the DC power supply voltage multiple times and recording their respective corresponding time points includes:

[0012] When the power converter is in the online operation state, during the stage when the bipolar junction transistor is in the off state and the resistor is put into operation, collect the DC power supply voltage at any two time points and record the time points.

[0013] In one embodiment, the monitoring and determining the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, the DC power supply voltages collected each time and their respective corresponding time points includes:

[0014] Determine the capacitance value C1 of the first aluminum electrolytic capacitor and the capacitance value C2 of the second aluminum electrolytic capacitor according to the following formula:

[0015]

[0016] Wherein, U SM1 (t) represents the DC power supply voltage collected for the first time, ta represents the time point when the DC power supply voltage is collected for the first time, U SM2 (t) represents the DC power supply voltage collected for the second time, tb represents the time point when the DC power supply voltage is collected for the second time, I represents the total output current, R represents the resistance value, and t1 represents the starting time point.

[0017] In one embodiment, during the stage when the bipolar junction transistor is in the off state and the resistor is put into operation, the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor remains unchanged.

[0018] In a second aspect, the present application provides an on-line monitoring device for capacitor capacitance values, including:

[0019] A collection module, configured to, when the power converter is in an online operation state, during a stage where the bipolar junction transistor is in an off state and the resistor is put into operation, collect the DC power supply voltage multiple times and record the respective corresponding time points.

[0020] An acquisition module, configured to acquire the starting time point of the stage where the bipolar junction transistor is in an off state and the resistor is put into operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0021] An online monitoring module, configured to monitor and determine the capacitance value of the first aluminum electrolytic capacitor and the capacitance value of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, each collected DC power supply voltage and its respective corresponding time point.

[0022] Wherein, a first capacitor branch, a second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0023] In one embodiment, the collection module includes:

[0024] A collection unit, configured to, when the power converter is in an online operation state, during a stage where the bipolar junction transistor is in an off state and the resistor is put into operation, collect the DC power supply voltage at any two time points and record the time points.

[0025] In a third aspect, the present application provides an auxiliary discharge network, including: a bipolar junction transistor and a resistor; the resistor is connected in series with the first aluminum electrolytic capacitor in the power converter to form a first capacitor branch; the first capacitor branch is connected in parallel with a second capacitor branch, and the second capacitor branch includes: the second aluminum electrolytic capacitor in the power converter; the bipolar junction transistor is connected in parallel with the resistor.

[0026] In a fourth aspect, the present application provides a capacitor capacitance value online monitoring system, including:

[0027] A microcontroller, the aforementioned auxiliary discharge network, and the aforementioned capacitor capacitance value online monitoring device;

[0028] The microcontroller is configured to control the closing and opening of the bipolar junction transistor.

[0029] In a fifth aspect, the present application provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, it implements the aforementioned capacitor capacitance value online monitoring method.

[0030] In a sixth aspect, the present application provides a computer-readable storage medium, on which computer instructions are stored, and when the instructions are executed by a processor, the on-line monitoring method for the capacitance value of a capacitor according to any one of claims 1 to 4 is implemented.

[0031] As can be seen from the above technical solutions, the present application provides an on-line monitoring method, device, system and auxiliary discharge network for the capacitance value of a capacitor. Among them, the method includes: when the power converter is in an on-line operation state, during the stage when the bipolar junction transistor is in an off state and the resistor is put into operation, the DC power supply voltage is collected multiple times and the corresponding time points are recorded; obtaining the start time point of the stage when the bipolar junction transistor is in an off state and the resistor is put into operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter; according to the start time point, the total output current, the resistance value, the DC power supply voltage collected each time and their corresponding time points, monitoring and determining the capacitance value of the first aluminum electrolytic capacitor and the capacitance value of the second aluminum electrolytic capacitor; wherein, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor, and can monitor the capacitance value of the capacitor when the power converter is in an on-line operation state, thereby improving the reliability of capacitor state monitoring; specifically, the auxiliary discharge circuit has a simple and reliable structure, and a simple and low-cost resistor and bipolar junction transistor BJT can be used to estimate the capacitance without interrupting the continuous operation of the power converter. The estimation process only requires an auxiliary discharge circuit; a high sampling frequency is not required, and only the bottom capacitor voltage and the total output current of the circuit are measured to estimate the capacitance; at the same time, the amount of data collected by the auxiliary discharge circuit is small and complex algorithms are not required; the working state of the parallel capacitor can be obtained more accurately, providing a basis for evaluating the operating state of the device. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 is the first flowchart of the on-line monitoring method for the capacitance value of a capacitor in the embodiment of the present application;

[0034] Figure 2 is the second flowchart of the on-line monitoring method for the capacitance value of a capacitor in the embodiment of the present application;

[0035] Figure 3 It is a schematic diagram showing the relationship between the auxiliary discharge circuit, the first aluminum electrolytic capacitor, the second aluminum electrolytic capacitor and the DC power supply in the application example of the present application;

[0036] Figure 4 It is a logic schematic diagram of the power converter in the application example of the present application;

[0037] Figure 5 It is a schematic structural diagram of the capacitor capacitance online monitoring device in the embodiment of the present application;

[0038] Figure 6 It is a schematic block diagram showing the system composition of the electronic device in the embodiment of the present application. Detailed implementation manners

[0039] In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0040] In the prior art, the quasi-online CM scheme in the capacitor state monitoring scheme needs to be under specific conditions, such as startup, shutdown and no-load, etc., and these conditions are usually not the normal operating states of the power converter. In the normal online operating state of the power converter, the capacitor will be subjected to different voltage and current conditions, and there is a risk that it is not applicable or inaccurate to estimate the capacitance value through the charge and discharge curve. Moreover, since the quasi-online CM scheme depends on the charge and discharge curve under specific conditions, it cannot provide continuous monitoring during the normal operation of the capacitor. Under normal operating conditions, the operating conditions of the capacitor are continuous and dynamically changing, and the quasi-online CM scheme cannot capture and analyze the charge and discharge curve in real time during this dynamic change, so continuous capacitance value estimation cannot be achieved, and it is not applicable to the online monitoring of the capacitor capacitance.

[0041] To solve the problems existing in the above prior art, the embodiments of the present application provide a method, device, system and auxiliary discharge network for online monitoring of capacitor capacitance, which can estimate the parallel capacitance online based on the large-signal transient trajectory. Through a simple and low-cost auxiliary discharge network, transient conditions can be generated without interrupting the normal operation of the converter. This method does not require a high sampling frequency, and only needs to measure the capacitor voltage and the output current of the circuit. After identifying the functional relationship between the capacitance and the discharge time, the capacitance value is obtained by calculating a system of binary equations.

[0042] Specifically, it will be described through the following respective embodiments.

[0043] In order to monitor the capacitance value of a capacitor when a power converter is in an online operation state, and thus improve the reliability of capacitor state monitoring, this embodiment provides a method for online monitoring of capacitor capacitance value, where the execution entity is an online monitoring device for capacitor capacitance value. The online monitoring device for capacitor capacitance value includes but is not limited to a server, such as Figure 1 As shown, the method specifically includes the following content:

[0044] Step 100: When the power converter is in an online operation state, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation, collect the DC power supply voltage multiple times and record the corresponding time points respectively.

[0045] Specifically, when the power converter is in an online operation state, a microprocessor can be used to control the bipolar junction transistor to be in the off state and the resistor to be in operation. The power converter can be a modular multilevel converter.

[0046] Step 200: Obtain the start time point of the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0047] Specifically, the time point when the microprocessor controls the bipolar junction transistor to turn off can be used as the start time point of the stage when the bipolar junction transistor is in the off state and the resistor is in operation. The total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor can represent the sum of the output current of the first aluminum electrolytic capacitor and the output current of the second aluminum electrolytic capacitor.

[0048] Step 300: Based on the start time point, the total output current, the resistance value, the DC power supply voltages collected each time and their corresponding time points, monitor and determine the capacitance value of the first aluminum electrolytic capacitor and the capacitance value of the second aluminum electrolytic capacitor; where the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0049] Specifically, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor can remain unchanged. It can be understood that the first aluminum electrolytic capacitor is the aluminum electrolytic capacitor in series with the resistor in the power converter; the second aluminum electrolytic capacitor can be the aluminum electrolytic capacitor in the power converter that is parallel to the first capacitor branch composed of the resistor and the first aluminum electrolytic capacitor; the DC power supply can be the DC power supply in the power converter.

[0050] To achieve the capacitance estimation of two parallel capacitors, as Figure 2 shown, in one embodiment, step 100 includes:

[0051] Step 101: When the power converter is in the online operation state, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation, collect the DC power supply voltage at any two time points and record the time points.

[0052] To achieve the capacitance estimation of two parallel capacitors, in one embodiment, for the monitoring and determination of the capacitance value of the first aluminum electrolytic capacitor and the capacitance value of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, the DC power supply voltages collected each time and their respective corresponding time points described in step 300, it includes:

[0053] Determine the capacitance value C1 of the first aluminum electrolytic capacitor and the capacitance value C2 of the second aluminum electrolytic capacitor according to the following formula:

[0054]

[0055] where, U SM1 (t) represents the DC power supply voltage collected for the first time, ta represents the time point when the DC power supply voltage is collected for the first time, U SM2 (t) represents the DC power supply voltage collected for the second time, tb represents the time point when the DC power supply voltage is collected for the second time, I represents the total output current, R represents the resistance value, and t1 represents the starting time point.

[0056] Furthermore, in this embodiment, the capacitance estimation method for two parallel capacitors is analyzed, and this solution can also be extended to multiple parallel capacitors.

[0057] To further illustrate this solution, the present application provides an application example of a method for online monitoring of the capacitance value of a capacitor, as Figure 3As shown, this method is implemented using an auxiliary discharge network, which consists of a resistor R and a small-current NPN transistor Q (i.e., bipolar junction transistor BJT). The resistor R is in series with the first aluminum electrolytic capacitor C1. The capacitive branch composed of the resistor R and the first aluminum electrolytic capacitor C1, the second aluminum electrolytic capacitor C2, and the DC power supply U SM are connected in parallel. The total output current I of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor can represent the sum of the output current I1 of the first aluminum electrolytic capacitor and the output current I2 of the second aluminum electrolytic capacitor. Q is controlled by a microcontroller to charge and discharge C1 and C2. The entire measurement process is divided into 3 stages. The specific description is as follows:

[0058] Stage 1 [t0 - t1]: The BJT is in the closed state, and the resistor R is not inserted into the circuit. After Laplace transform, the currents flowing through C1 and C2 and the output current can be expressed as:

[0059]

[0060] In the formula, I1(s) and I2(s) are the currents of C1 and C2 respectively, U SM (s) is the DC power supply voltage, I(s) is the output current of the circuit, s is the complex frequency, and the complex frequency is a variable after converting I from the time domain t to the complex frequency domain s. C1 is the capacitance value of the first aluminum electrolytic capacitor, and C2 is the capacitance value of the second aluminum electrolytic capacitor.

[0061] Stage 2 [t1 - t2]: The BJT is in the open state, and R is put into operation. At this time, the currents of C1 and C2 can be expressed as:

[0062]

[0063] From (2), it can be solved:

[0064]

[0065] Converting formula (3) into the time domain form and assuming that the output current I remains unchanged, we can get:

[0066]

[0067] Stage 3 [t2 - t3]: The BJT is in the closed state, C1 starts to charge, and C2 starts to discharge. This time interval should be long enough to make the voltages of C1 and C2 return to U SM (t).

[0068] Since the service life of aluminum electrolytic capacitors is up to thousands of hours, the change speed of their capacitance is slow. To reduce the power loss and voltage stress of C1 during the charging / discharging process, the measurement process is only carried out several times every few hours, and each time lasts for a few seconds.

[0069] The capacitance estimation is based on Stage 2. By measuring the voltage U at any two moments within t1 - t2 SM and recording the time t, substituting into Formula (4) can calculate the capacitance values of capacitors C1 and C2 respectively, thereby enabling the monitoring of the capacitance and providing a basis for evaluating the operating state of the capacitance. The structure of the power converter in this application example can be as Figure 4 shown. The power converter may include: arm cp, arm bp, arm ap, arm cn, arm bn, and arm an. Arm cn may include: valve tower 1 and valve tower 2. Valve tower 2 may include: multiple sub - modules SM1, SM2... SM k ... SM N ,SM k includes: insulated gate bipolar transistors IGBT1 and IGBT2, etc.

[0070] At the software level, in order to monitor the capacitance value of the capacitor when the power converter is in an online operating state, and thus improve the reliability of capacitor state monitoring, this application provides an embodiment of a capacitor capacitance online monitoring device for implementing all or part of the content in the capacitor capacitance online monitoring method. Refer to Figure 5 ,the capacitor capacitance online monitoring device specifically includes the following content:

[0071] Acquisition module 01, used to collect the DC power supply voltage multiple times and record their respective corresponding time points when the power converter is in an online operating state, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation;

[0072] Obtaining module 02, used to obtain the starting time point of the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter;

[0073] Online monitoring module 03, used to monitor and determine the capacitance value of the first aluminum electrolytic capacitor and the capacitance value of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, each collected DC power supply voltage and their respective corresponding time points; wherein, the first capacitance branch and the second capacitance branch are connected in parallel with the DC power supply; the first capacitance branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitance branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0074] In one embodiment, the acquisition module includes:

[0075] The acquisition unit is configured to collect the DC power supply voltage at any two time points and record the time points during the stage when the bipolar junction transistor is in the off state and the resistor is in operation when the power converter is in the online operation state.

[0076] The embodiments of the capacitor capacitance online monitoring device provided in this specification can specifically be used to execute the processing flow of the embodiments of the above-mentioned capacitor capacitance online monitoring method. Its functions will not be elaborated here, and reference can be made to the detailed description of the embodiments of the above-mentioned capacitor capacitance online monitoring method.

[0077] To further illustrate this solution, the present application provides an embodiment of an auxiliary discharge network. In this embodiment, the auxiliary discharge network includes: a bipolar junction transistor and a resistor; the resistor is connected in series with the first aluminum electrolytic capacitor in the power converter to form a first capacitor branch; the first capacitor branch is connected in parallel with a second capacitor branch, and the second capacitor branch includes: the second aluminum electrolytic capacitor in the power converter; the bipolar junction transistor is connected in parallel with the resistor.

[0078] To further illustrate this solution, the present application provides an embodiment of a capacitor capacitance online monitoring system. In this embodiment, the capacitor capacitance online monitoring system includes: a microcontroller, the above-mentioned auxiliary discharge network, and the above-mentioned capacitor capacitance online monitoring device; the microcontroller is configured to control the closing and opening of the bipolar transistor.

[0079] Figure 6 Schematic diagram of the physical structure of the electronic device provided by the embodiment of the present invention, as Figure 6 shown, the electronic device includes: a memory 601, a processor 602, and a computer program stored on the memory 601 and executable on the processor 602. When the processor 602 executes the computer program, the following method is implemented:

[0080] Step 100: When the power converter is in the online operation state, during the stage when the bipolar junction transistor is in the off state and the resistor is in operation, collect the DC power supply voltage multiple times and record the corresponding time points respectively.

[0081] Step 200: Obtain the starting time point of the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0082] Step 300: Monitor and determine the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor based on the start time point, the total output current, the resistance value, the DC power supply voltages collected each time, and their respective corresponding time points; wherein, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0083] This embodiment discloses a computer program product, which includes a computer program. When the computer program is executed by a processor, the following method is implemented:

[0084] Step 100: When the power converter is in the online operation state, in the stage where the bipolar junction transistor is in the off state and the resistor is put into operation, collect the DC power supply voltage multiple times and record their respective corresponding time points.

[0085] Step 200: Obtain the start time point of the stage where the bipolar junction transistor is in the off state and the resistor is put into operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0086] Step 300: Monitor and determine the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor based on the start time point, the total output current, the resistance value, the DC power supply voltages collected each time, and their respective corresponding time points; wherein, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0087] This embodiment provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the following method is implemented:

[0088] Step 100: When the power converter is in the online operation state, in the stage where the bipolar junction transistor is in the off state and the resistor is put into operation, collect the DC power supply voltage multiple times and record their respective corresponding time points.

[0089] Step 200: Obtain the start time point of the stage where the bipolar junction transistor is in the off state and the resistor is put into operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter.

[0090] Step 300: Determine the capacitance values of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor by monitoring based on the starting time point, the total output current, the resistance value, the DC power supply voltages collected each time and their respective corresponding time points; wherein, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

[0091] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0092] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in Figure 1 one or more flows Figure 1 or multiple flows and / or blocks

[0093] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one or more flows Figure 1 or multiple flows and / or blocks

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one or more flows Figure 1 or multiple flows and / or blocks

[0095] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0096] The above-described specific embodiments have further elaborated on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for online monitoring of capacitor capacitance, characterized in that: include: When the power converter is in an online operation state, at the stage when the bipolar junction transistor is in an off state and the resistor is put into operation, the DC power supply voltage is collected multiple times and the corresponding time points are recorded; Acquire the starting time point of the stage in which the bipolar junction transistor is in an off state and the resistor is put into operation, the resistance value of the resistor, and the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor in the power converter; Monitoring and determining the capacitance of the first aluminum electrolytic capacitor and the capacitance of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, the DC power supply voltage collected each time and their respective corresponding time points; Among them, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

2. The method for online monitoring of capacitor capacitance according to claim 1, characterized in that: The method of collecting the DC power supply voltage multiple times and recording the corresponding time points when the bipolar junction transistor is in the off state and the resistor is put into operation comprises: When the power converter is in an online operation state, during the stage when the bipolar junction transistor is in an off state and the resistor is put into operation, the DC power supply voltage is collected at any two time points and the time points are recorded.

3. The capacitor capacitance online monitoring method according to claim 1, characterized in that: The monitoring and determining the capacitance of the first aluminum electrolytic capacitor and the capacitance of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, the DC power supply voltage collected each time and their respective corresponding time points includes: The capacitance C1 of the first aluminum electrolytic capacitor and the capacitance C2 of the second aluminum electrolytic capacitor are determined according to the following formula: Among them, U SM1 (t) represents the DC power supply voltage collected for the first time, ta represents the time point when the DC power supply voltage is collected for the first time, U SM2 (t) represents the DC power supply voltage collected for the second time, tb represents the time point of collecting the DC power supply voltage for the second time, I represents the total output current, R represents the resistance value, and t1 represents the starting time point.

4. The method for online monitoring of capacitor capacitance according to claim 1, characterized in that: During the stage when the bipolar junction transistor is in the off state and the resistor is in operation, the total output current of the first aluminum electrolytic capacitor and the second aluminum electrolytic capacitor remains unchanged.

5. A capacitor capacitance online monitoring device, characterized in that: include: The acquisition module is used to acquire the DC power supply voltage multiple times and record the corresponding time points when the power converter is in an online operation state and the bipolar junction transistor is in a disconnected state and the resistor is put into operation; An acquisition module, used to acquire a starting time point of a stage in which the bipolar junction transistor is in an off state and the resistor is put into operation, a resistance value of the resistor, and a total output current of a first aluminum electrolytic capacitor and a second aluminum electrolytic capacitor in the power converter; An online monitoring module, used to monitor and determine the capacitance of the first aluminum electrolytic capacitor and the capacitance of the second aluminum electrolytic capacitor according to the starting time point, the total output current, the resistance value, the DC power supply voltage collected each time and their respective corresponding time points; Among them, the first capacitor branch and the second capacitor branch are connected in parallel with the DC power supply; the first capacitor branch includes: the resistor and the first aluminum electrolytic capacitor connected in series; the second capacitor branch includes: the second aluminum electrolytic capacitor; the bipolar junction transistor is connected in parallel with the resistor.

6. The capacitor capacitance online monitoring device according to claim 5, characterized in that: The acquisition module comprises: The acquisition unit is used to acquire the DC power supply voltage at any two time points and record the time points when the power converter is in an online operation state and the bipolar junction transistor is in a disconnected state and the resistor is put into operation.

7. An auxiliary discharge network, characterized in that: include: Bipolar junction transistors and resistors; The resistor is connected in series with the first aluminum electrolytic capacitor in the power converter to form a first capacitance branch; The first capacitor branch is connected in parallel with a second capacitor branch, and the second capacitor branch includes: a second aluminum electrolytic capacitor in the power converter; The bipolar junction transistor is connected in parallel with the resistor.

8. A capacitor capacitance online monitoring system, characterized in that: include: A microcontroller, an auxiliary discharge network as claimed in claim 7, and an online monitoring device for capacitor capacitance as claimed in claim 5 or 6; The microcontroller is used to control the closing and opening of the bipolar junction transistor.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the online monitoring method for capacitor capacitance according to any one of claims 1 to 4 is implemented.

10. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the instructions are executed by the processor, the online monitoring method for capacitor capacitance according to any one of claims 1 to 4 is implemented.

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